COLUMBIA, S.C. (AP) -- Days of torrential rains kept much of South Carolina and its capital gripped by floodwaters early Monday as emergency responders promised renewed door-to-door searches for anyone still trapped after a weekend deluge and hundreds of rescues.
At least seven weather-related deaths have been blamed on the vast rainstorm.
Heavy rain kept falling into the early hours Monday around the Carolinas from the storm that began swamping the Southeast late last week, part of an unprecedented low pressure system that dumped more than 18 inches on one spot alone in Columbia, the South Carolina capital.
The rainstorm dumped so much water on South Carolina and parts of several surrounding states that even the weather experts said they were astonished.
"The flooding is unprecedented and historical," said Dr. Marshall Shepherd, a meteorologist and director of the atmospheric sciences program at the University of Georgia, in an email to The Associated Press.
He said the unique double punch of the upper level low — aided by a "river" of tropical moisture in the atmosphere from Hurricane Joaquin spinning far out in the Atlantic — gave the monster rainstorm its punch.
The deluge made for otherworldly scenes in the state capital of Columbia as floodwaters nearly touched the stoplights Sunday at one downtown intersection. Rainwater cascaded like a waterfall over jagged asphalt where a road sheered apart and many cars were submerged under flooded streets.
The flooding forced hundreds of weekend rescues and threatened the drinking water supply for hundreds of thousands in Columbia, with officials there warning some could be without potable water for days because of water main breaks. Electrical outages affecting thousands also were reported. Elsewhere, nearly 75 miles of Interstate 95 — the main link from the Southeast U.S. to the Northeast — had to be closed for a time.
Officials counted several hundred water rescues at one point Sunday. But Columbia Fire Chief Aubry Jenkins said in an interview that there were quickly too many rescues to even tally. Among those rescued were a woman and baby lifted to safety by helicopter.
Police in the flooded South Carolina capital of Columbia say they and other emergency crews would continue with "concentrated search and rescue operations" early Monday.
Columbia Police Chief William Holbrook issued a statement saying the operations would check for any people in the city and nearby Richland County still needing evacuation from flooded areas. He urged anyone still needing help to call 911, saying they would be taken out on military vehicles and bused to shelters.
"The operation will also include overall welfare checks," he said, adding crews will mark the front doors of homes checked with a fluorescent orange X once searched.
After a nightmarish weekend marked by scenes of swift-water rescues, bridge washouts and small dams giving way, reality was setting in Monday as people waited and hoped for the rains to ease. Some reports indicate the sun could peek out Tuesday. Many recovery tasks lay ahead.
Several schools and colleges, including the University of South Carolina, canceled classes Monday and some businesses planned to stay shuttered.
Numerous roads and bridges around the state were washed out or under water. All will have to be checked to see if they are structurally sound or repaired.
"It's going to be week or months before all of the roads are assessed," state Adjutant General Bob Livingston Jr. said.
People were told to stay off roads and remain indoors until floodwaters recede, and a curfew was in place overnight for Columbia and two surrounding counties. The capital city told all 375,000 of its water customers to boil water before drinking because of water line breaks and rising water threatening a treatment plant. Nearly 30,000 customers were without power at one point.
One of the hardest hit areas in Columbia was near Gills Creek, where a weather station recorded more than 18 inches of rain — or more than a third of the city's average yearly rainfall — nearly all of it in 24 hours. The creek was 10 feet above flood stage, spilling floodwaters that almost reached the stoplights at a four-lane intersection.
Rescue crews used boats to evacuate the family of Jeff Whalen, whose house backs up on the creek.
"I got up around 6:15 and a neighbor called to tell us we should get out as soon as we can," Whalen said. "About that point it was about a foot below the door and when we left it was a foot in the house. It came quickly obviously."
Along the coast, rainfall had exceeded two feet since Friday in some areas around Charleston, though conditions had improved enough that residents and business owners were allowed downtown on a limited basis.
Charleston Mayor Joe Riley said he's never seen flooding as bad in his 40 years as mayor.
"This was a record storm," he said.
At least seven weather-related deaths have been reported since rains began spreading over the Eastern Seaboard, which appeared to dodge the full fury of Hurricane Joaquin which was rapidly weakening as it veered every further out into the Atlantic.
One death was reported in the Columbia area Sunday. In another incident, a woman was killed when her SUV was swept into flood waters in Columbia. Richland County Coroner Gary Watts said the woman's body was found Sunday afternoon, about 12 hours after she disappeared in flood waters near downtown Columbia.
Three people died in separate weather-related traffic accidents in South Carolina on Friday and Saturday, the Highway Patrol said. In North Carolina, a driver died on a rain-slickened road on Saturday, according to that state's Highway Patrol. On Thursday, a woman drowned in her car in Spartanburg, South Carolina, while a passenger in North Carolina was killed when a tree fell onto the highway.
The flooding also prompted acts of kindness in Columbia.
Rawlings LaMotte, 38, a residential real estate broker, said he and a friend got into a small motorboat and ended up ferrying several people to safety, including a man who had been out of town and found roads to his home blocked.
"Until you've experienced something like this, you have no idea how bad it really is," LaMotte said.
Julie Beitz, president of the Forest Acres neighborhood association, said she paid for a stranger to stay at Extended Stay after her car was submerged on a nearby flooded road.
"You do anything you can to help people," Beitz said.